A battery pack is used with various kinds of electronic appliances as a battery that is capable of being charged, and such battery pack houses one or a plurality of battery cells in a battery case.
There are some battery cells that are of a flat square pole in shape, and it is efficient in terms of space for these battery cells to be housed in a square pole-like battery case that is one size larger than the battery cell.
In addition, the battery pack is provided with a negative pole side tab creeping over the side of a battery can from the battery can bottom to the battery can lid side in order to provide a battery terminal at one end of the battery pack or in a region in the direction of one end thereof.
Further, in the case where a plurality of battery cells are connected in series, an intermediate connection tab is provided for connecting the battery can bottom with a positive pole terminal part of adjacent another battery cell, and the intermediate connection tab is provided to creep over the side of the battery can as does the above-mentioned negative pole side tab.
Meanwhile, when these negative pole side tab and intermediate connection tab are disposed creeping over the side of the battery can, there is interposed an insulation sheet in-between.
In addition, there are provided some battery packs in which the above-mentioned negative pole side tab and the intermediate connection tab are respectively divided in two, and PTC (positive temperature coefficient) is interposed between these divided tab piece and tab piece so as to break supply of electric power when the temperature of the battery cell becomes high.
Further, with the square pole-like battery cell, the central portion of a rectangle tends to bulge out at a time of the battery cell being charged.
Because of the above-mentioned fact, the battery case needs to be formed to be one or two size as large as the outer shape of the battery cell.
However, in the case where the battery case is formed larger than the battery cell, there occurs a problem in which the battery cell become wobbly in the inside thereof.
When the battery cell becomes wobbly in the battery case, the above-mentioned negative pole side tab and the positive pole side tab that are connected to the battery terminal repeat deformation that leads to a trouble in which these tabs are damaged as the battery terminal is conventionally fixed to the battery case.
In addition, when the battery cell become wobbly, the above-mentioned negative pole side tab and the intermediate connection tab move and shift from the insulation sheet, resultantly leading to a trouble such as a short circuit of power.